The secretary joined DIA Director Army Lt. Gen. Ronald L. Burgess Jr., Director of National Intelligence James R. Clapper, and more than 500 distinguished guests at a ceremony here celebrating the agency’s 50th anniversary.

During the ceremony, defense officials from Canada, Australia and the United Kingdom presented Burgess with gifts, and a tribute was made to fallen DIA colleagues.

“In commemorating this milestone,” Panetta said, “we all pay tribute to DIA’s half-century of extraordinary work defending our nation against a multitude of threats, a multitude of challenges, from the height of the Cold War to the post-9/11 conflicts.”

A lot has changed in the last 50 years, the secretary added, “but one thing that remains the same is that we cannot accomplish our military objectives -- it’s a fundamental principle -- … without good intelligence. The two have to work together if we’re going to achieve the ultimate victory.”

The DIA’s vital work makes the U.S. military vastly more effective and lethal, Panetta said, and America a stronger and more secure nation.

“As we take this moment to reflect on the last 50 years,” Burgess told the audience, “it is important to consider the decisions made by our nation’s leaders at a very different time and place, and how those decisions and deliberations influence our world today.”

In the summer of 1961, he said, during deliberations over the creation of DIA, the Joint Chiefs of Staff wrote in a report to then Defense Secretary Robert McNamara that “‘national intelligence and military intelligence are indivisible in practice.’”

Seven former DIA directors also attended, including Clapper, who led the agency from 1992 to 1995.

“We ought to give a thought to just how fortunate we are to have not one, but two secretaries of defense in succession who both served as directors of the Central Intelligence Agency,” Clapper said, “and who obviously understand, support and care about intelligence.”

Panetta said his own DIA connection began in the mid-1960s when he was an Army intelligence officer and one of his first assignments was to the DIA office in Washington.

“Since then,” he said, “I’ve always had a great respect for the work of DIA, which has become a central part of the military and intelligence community’s efforts around the world.”

DIA was born in an era when the nation faced down a single adversary, and the potential consequences of conflict with the Soviet Union were so profound that it was critical to have the most accurate, prompt information “to prevent what we all knew would be global calamity,” Panetta said.

Less than a year later, he added, DIA faced its first great test when the Cuban missile crisis brought the world to the brink of a world war.

“I remember all of those scenes from that moment. The iconic photos of the surface-to-air missiles arranged across a Cuban airfield that provided direct evidence of the threat to our homeland,” he said.

Months after the crisis, Panetta said, President John F. Kennedy called on John Hughes, special assistant to the DIA director, to deliver a nationally televised briefing to reassure the nation that the Soviet missiles had been withdrawn.

“It was a moment that defined the DIA as a vital vehicle for keeping America safe,” he said. “And that sentiment is as true today as it was 50 years ago.”

Another defining moment for the United States and for the DIA was Sept. 11, 2001, Panetta said.

In the decade since the terrorist attacks, the secretary said, DIA has emerged stronger, better integrated and more integral to the fight against America’s terrorist enemies, and a driving force behind the comprehensive military-intelligence collaboration under way to defeat al-Qaida.

“We have come together as one to integrate the efforts among the DIA, DOD, CIA and all of the intelligence communities in the executive branch to become part of one great accomplishment of the post-9/11 era,” Panetta said, adding that the entire world saw the results of this teamwork with the operation that took down Osama bin Laden.

“Whether forward deployed overseas to support the war-fighting effort or from desks here in the Washington area, the men and women of the DIA stand more than ever at the center of our military’s efforts worldwide,” the secretary said.

In Iraq and Afghanistan, Panetta added, DIA has provided essential tools and intelligence for battling insurgencies and locating high-value targets.

“All the while,” he said, “DIA has remained vigilant, never taking its eye off the emerging threats we face -– monitoring North Korea’s and Iran’s nuclear ambitions, and looking at foreign military capabilities in space and cyberspace.”

This new era for DIA and the rest of the intelligence community builds on the proud traditions of the last 50 years, the secretary said, and extended to the agency his deep admiration for its achievements.

“I would like to say that as secretary of defense, and I would like to say that on behalf of the intelligence community that I had the honor to be a part of in my time here in Washington, a grateful nation … is safer and more secure due to your tireless efforts,” Panetta said.

“On behalf of the entire Department of Defense and on behalf of the American people,” he continued, “thank you for your continued outstanding devotion to duty to this country, thank you for your service, thank you for your sacrifice, thank you for all you do to protect this nation.”

If the test of DIA is whether or not it has made a difference, the secretary said, “I think that history will look at the DIA and say they did a job well done … and the result is that we have a safer and more secure life for our children in the future.”